1. Field of the Invention
The present invention relates to a machine tool control system and, more specifically, to a machine tool control system in which a metal tool or mold predetermined by an automatic programming unit is retrieved from a tool storage of a machine tool in advance, with reference to the characteristic properties of the metal mold, and set in a turret of a machine tool.
2. Prior Art
In recent years, in the field of machining for controlling various types of machine tools which is directed toward multi-type small-quantity production, FMS (Flexible Manufacturing System) has been coming into wide use.
Generally speaking, with FMS a plurality of device controllers are connected to a single main controller which creates a schedule program for the schedule operation of various types of devices. A description is given of a machine tool control system as an example of such an FMS.
FIG. 1 is a schematic diagram of a machine tool control system of the prior art. In the machine tool control system of FIG. 1, a tool center 1 and a field terminal 4 (to be referred to as "controller" hereinafter) for transferring a machining program to a CNC device 3 for controlling a turret punch press 2 as a machine tool are connected to an Ethernet LAN 5.
To the turret punch press 2 is connected a peripheral equipment section 7 including material warehouse equipment, product warehouse equipment and the like. Each device of this peripheral equipment section 7 operates in accordance with the sequence of a line control board 8. A group of the peripheral equipment section 7, the turret punch press 2 and the CNC device 3 is referred to as an "FMS line" in the following description.
The turret punch press 2, as shown in FIG. 1, comprises a tool storage 11 for storing a plurality of metal molds and an automatic metal mold exchange unit 17 (to be abbreviated as "ATC" hereinafter) for taking out a metal mold specified by the CNC device 3 from the tool storage 11 and setting it in the metal mold mount station 15 of a turret 13.
The tool center 1 is provided with a plurality of schedule files 21 for storing machining schedules each of which consist of data including the date, type of machining, materials, quantities, spots to be machined and the like, and machining program files 23 for storing a plurality of machining programs for carrying out control in accordance with type of machining.
An automatic programming unit 25 is arranged in the vicinity of the tool center 1. This automatic programming unit 25 determines the address (to be referred to as "metal mold address" hereinafter) of each box 11a of the tool storage 11 and gives numbers to these metal mold addresses to assign the numbers to metal molds.
How to assign metal molds in the tool storage 11 to the metal mold mount stations 15 of the turret 13 timely based in a machining schedule is determined from data on the past use conditions, and this information is stored in a metal mold information file 27 as used metal mold setup information.
A description is subsequently given of the operation of the machine tool control system of the prior art constituted above.
The controller 4 communicates with the tool center 1 to read the machining schedule Hi of the day from the schedule files 21 and a machining program Mi for carrying out this machining schedule Hi properly from the machining program files 23 and reads metal mold setup information Ki for the machining program Hi from the metal mold information file 27 of the automatic programming unit 25.
The controller 4 draws a first schedule hi from the machining schedule Hi as well as a machining program mi for the schedule hi and used metal mold setup information ki specified by the machining program mi. Thereafter, this machining program mi and the used metal mold setup information ki are transferred to the CNC device 3 by memory transfer or by a DNC transfer system.
The CNC device 3 transmits the metal mold setup information ki to the ATC 17 of the turret punch press 2.
The ATC 17 turns the turret 13 based on the used metal mold setup information ki. The ATC 17 also takes out a metal mold at a metal mold address specified by the used metal mold setup information ki from the box of the tool storage 11 and sets it in the metal mold mount station of the turret 13.
When a metal mold in the tool storage is exchanged by an operator, the controller 4 detects the occurrence of a setup plan for manual metal mold exchange through the line control board 8.
Due to the occurrence of a setup plan for manual metal mold exchange, the controller 4 exchanges the used metal mold setup information ki to be read from the automatic programming unit 25.
However, a metal mold in a box of the tool storage may be changed to another metal mold by a field operator.
Therefore, when a metal mold in a box of the tool storage at a metal mold address specified by the used metal mold setup information obtained by the ATC from the automatic programming unit is set in a metal mold mount station of the turret, there is the possibility that a target metal mold may not be set.
When a metal mold in the tool storage is exchanged by an operator, the controller 4 needs to exchange used metal mold setup information read from the automatic programming unit by temporarily stopping the line.
That is, when line operation is carried out based on predetermined used metal mold setup information, there is such a problem that, if the metal mold of tool storage is different, operation is suspended frequently.
Further, there is another problem that the transfer time of the controller 4 is long because it transfers a machining program and used metal mold setup information together by DNC transfer system.
For instance, it takes approximately 3 to 4 seconds longer to transfer 1 KB metal mold setup information only at a transfer speed of 9,600 bps.
Further, the controller 4 transfers a machining program and used metal mold setup information together to the CNC device.
Therefore, since the CNC device must separate the machining program and the metal mold setup information to analyze the metal mold setup information when it transfers the metal mold setup information to the ATC, it takes long to start machining.